Study to Evaluate Safety, Tolerability and Efficacy of UCB7665 in Subjects With Primary Immune Thrombocytopenia

Inclusion criteria

• Subject has a diagnosis of primary immune thrombocytopenia (ITP) for a minimum of 3 months prior to Screening Visit
• Subject has a platelet count <30x10^9/L at Screening and <35x10^9/L at Baseline (Visit 2)
• Subject has a current or history of a peripheral blood smear consistent with ITP
• Subject has responded to previous ITP therapy (according to the judgment of the investigator)

Exclusion criteria

• Subject has an immunoglobulin G (IgG) level <=6g/L at Screening Visit
• Subject has a partial thromboplastin time (PTT) >=1.5x upper limit of normal (ULN) or International Normalized Ratio (INR) >=1.5 at Screening Visit
• Subject has renal and/or liver impairment defined as:

• Serum creatinine level of >=1.4 mg/dL for females and >=1.5 mg/dL for males at Screening Visit
• Subject has planned an elective surgical procedure in the coming 6 months
• Subject has evidence of a secondary cause of primary immune thrombocytopenia purpura
• Subject has a history of clinically relevant ongoing chronic infections
• Subject has a family history of primary immunodeficiency
• Subject has a clinically relevant active infection or has had a serious infection within 6 weeks prior to the first dose of IMP
• Subject has a history of known inflammatory bowel disease, diverticular disease, and gastric or esophageal ulceration
• Subject has experienced gastrointestinal bleed in the last 6 months prior to Screening Visit and/or has current gastritis or esophagitis
• Subject has a medical history of thrombosis
• Subject has a history of coagulopathy disorders other than ITP
• Subject has received a live vaccination within 8 weeks prior to the Baseline Visit; or intends to have a live vaccination during the course of the study or within 7 weeks following the final dose of IMP
• Subject has had prior treatment with rituximab in the 6 months prior to the Baseline Visit
• Subject has not completed the washout period for the immunosuppressants, biologics and other therapies